In the past year we identified those glycerolipids which are enriched with arachidonic acid and furthermore showed that the iris, under physiologyical conditions, can release and subsequently convert arachidonate into prostaglandins. To further characterize the molecular mechanism(s) underlying the release and subsequent metabolism of arachidonate into prostaglandins, we propose to carry out the following studies: (1) Investigate the relationship between glycerolipids and prostaglandins biosynthesis with time. Hopefully, the results from this study will give us information on the arachidonate pool which is the source for prostaglandin biosynthesis in the iris. (2) Investigate the relationship between receptor activation and prostaglandin release. (3) Determine the type of receptors which are involved in prostaglandin release. (4) Study the influence of the ionic environment and pharmacological agents on the metabolism of arachidonate and its subsequent conversion into prostaglandins.